1. Field of the Invention
The invention relates to interactive television systems and more particularly to management of application modules which are delivered to an interactive television receiver.
2. Description of the Related Art
Interactive television systems enable television sets to be used to provide various new means for providing services to viewers. Interactive television systems are capable of displaying text and graphic images in addition to typical video program streams. Interactive television systems are also capable of registering viewer actions or responses. Proposed features of interactive television include a variety of marketing, entertainment and educational capabilities such as allowing a user to interact with televised programs by ordering advertised products or services, competing against contestants in a game show, or requesting specialized information regarding particular programs.
Typically, a broadcast service provider generates an interactive television signal for transmission to a viewer""s television. The interactive television signal includes an interactive portion consisting of application code or control information, as well as an audio-video portion consisting of a television program. The broadcast service provider combines the audio-video and interactive portions into a single signal for transmission to a receiver connected to the user""s television. The signal is generally compressed prior to transmission and transmitted through typical broadcast channels, such as cable television (CATV) lines or direct satellite transmission systems.
The interactive functionality of the television is controlled by a set-top box connected to the television. The set-top box receives the signal transmitted by the broadcast service provider, separates the interactive portion from the audio-video portion and decompresses the respective portions of the signal. The set-top box uses the interactive information to, for example, execute an application while the audio-video information is transmitted to the television. The set-top box may combine the audio-video information with interactive graphics or audio generated by the interactive application prior to transmitting the information to the television. The interactive graphics and audio may present additional information to the viewer or may prompt the viewer for input. The set-top box may provide viewer input or other information to the broadcast service provider via a modem connection.
Interactive television applications may consist of a set of program modules. The set of modules forming an application is typically self-contained in that all of the code needed by the application is in the set of modules. The first module is a directory module which identifies all of the modules which are part of the application. The entire set of modules, which is listed in the directory module, is transmitted via the broadcast channel to the set-top box and the application is executed. If a first interactive television application has completed execution and a second is to be executed, the directory and other modules of the second application are transmitted to the set-top box and the second application is executed. The entire set of modules used by the second application are transmitted even though some of the modules might be identical to modules used by the first application.
One of the advantages of designing software applications in a modular fashion is the ability to share modules between applications. The advantages of modularity may include conserving the limited amount of memory in a set-top box which can be used for interactive applications, reducing the time required to download applications from a broadcast station to a set-top box and reducing the amount of application code which must be written by allowing modules to be shared. The components of an application, however, may reside in different carousels (sets of modules, as described in more detail below) or in modules which may not be available at the time the application begins execution. It is therefore desirable to implement a system for management of the different modules. It would be advantageous for this management system to be capable of handling modules which have not yet been received and which may have to be extracted from an interactive television signal. Further, it would be advantageous for this management system to be capable of simultaneously monitoring several sources (e.g., a broadcast channel and a modem channel) for the modules needed by an application.
The invention comprises a system and method for managing modules of interactive television applications. One embodiment of the invention includes a set-top box configured with several input ports for receiving one or more interactive television signals which may embody the carousel modules. The interactive television signals typically comprise packets of compressed data corresponding to modules of an interactive television application, television programs, or other interactive television data. (xe2x80x9cTelevision programxe2x80x9d as used herein refers generally to any type of audio and/or video programming which is normally viewed on a television.) The various types of packets are generally time multiplexed with each other. The set-top box monitors the input ports to determine whether a packet received at the input port contains module data and, if so, whether the module should be processed and stored in the set-top box. If the system determines that the module should be stored, the packets corresponding to the module are extracted from the interactive television signal. When all of the packets corresponding to the module have been extracted from the interactive television signal, the module is processed and made available for execution.
If there is no interactive television application executing in the set-top box, the system monitors the input ports for auto-loading modules, such as application directory modules. When one of these application directory modules is detected, the system begins collecting packets containing data from the directory module. When all of these packets have been collected, the system reconstructs the directory module and authenticates it. The system then monitors the input ports for the carousel modules (i.e., those listed in the directory module,) stores the corresponding packets and reconstructs the modules for use by the application corresponding to the carousel.
The executing application may request modules which are not yet available in the set-top box. These requests are stored by the system, which monitors the input ports for the corresponding modules. The system collects the packets of these modules when they are detected at the input ports, then stores the modules. The system thus matches incoming modules with pending requests and makes the modules available for execution. The system may provide for modules which are in greater demand among subscribers of the system to be transmitted to all of the subscribers via a broadcast channel, while modules which are in less demand are transmitted to individual subscribers via a modem channel.